Holmes’s dissent is to fans of the First Amendment as Pavarotti’s rendition of “Nessun Dorma” is to opera buffs, except Holmes didn’t take his act on the road. It’s a brief, tour de force exposition of the idea that governments should only in the most exceptional circumstances interfere with speech and expression.

Why does it come to mind now? Maybe it’s a light in dark, uncertain times. Although these are times, too, when the central premise of Holmes’s dissent — that “the best test of truth is the power of the thought to get itself accepted in the competition of the market” — is contradicted by the recent triumph of unashamed bullshit.

Anyway, here’s the oft-quoted passage from the dissent:

Persecution for the expression of opinions seems to me perfectly logical. If you have no doubt of your premises or your power, and want a certain result with all your heart, you naturally express your wishes in law, and sweep away all opposition. To allow opposition by speech seems to indicate that you think the speech impotent, as when a man says that he has squared the circle, or that you do not care wholeheartedly for the result, or that you doubt either your power or your premises. But when men have realized that time has upset many fighting faiths, they may come to believe even more than they believe the very foundations of their own conduct that the ultimate good desired is better reached by free trade in ideas — that the best test of truth is the power of the thought to get itself accepted in the competition of the market, and that truth is the only ground upon which their wishes safely can be carried out. That, at any rate, is the theory of our Constitution. It is an experiment, as all life is an experiment. Every year, if not every day, we have to wager our salvation upon some prophecy based upon imperfect knowledge. While that experiment is part of our system, I think that we should be eternally vigilant against attempts to check the expression of opinions that we loathe and believe to be fraught with death, unless they so imminently threaten immediate interference with the lawful and pressing purposes of the law that an immediate check is required to save the country.

One of Holmes’s coinages there — “fighting faiths” — has always thrown me a little. My own clarification, after a little reading: He’s referring to ideals — freedom, for instance — that one feels compelled to fight for.